zero: resource bundle reconciler (#4445)

internal/zero/reconciler/bundles_format.go

@@ -0,0 +1,35 @@
+package reconciler
+
+import (
+	"bufio"
+	"errors"
+	"fmt"
+	"io"
+
+	"google.golang.org/protobuf/encoding/protodelim"
+
+	"github.com/pomerium/pomerium/pkg/grpc/databroker"
+)
+
+var unmarshalOpts = protodelim.UnmarshalOptions{}
+
+// ReadBundleRecords reads records in a protobuf wire format from src.
+// Each record is expected to be a databroker.Record.
+func ReadBundleRecords(src io.Reader) (RecordSetBundle[DatabrokerRecord], error) {
+	r := bufio.NewReader(src)
+	rsb := make(RecordSetBundle[DatabrokerRecord])
+	for {
+		record := new(databroker.Record)
+		err := unmarshalOpts.UnmarshalFrom(r, record)
+		if errors.Is(err, io.EOF) {
+			break
+		}
+		if err != nil {
+			return nil, fmt.Errorf("error reading protobuf record: %w", err)
+		}
+
+		rsb.Add(DatabrokerRecord{record})
+	}
+
+	return rsb, nil
+}